Magnetic tape cassettes (eg audio and video tape cassettes) are supplied commercially either as blank tape or as prerecorded tape. In both cases, the cassette comprises two rotatable hubs, two lengths of leader tape one secured to each hub and a predetermined length of magnetic use tape having its ends spliced to the two leaders.
In manufacture of a cassette tape, magnetic tape is loaded to a leadered cassette, ie a cassette containing a relatively short length of leader secured by one end to one hub and by the other end to the other hub. Such a leadered cassette for audio use is known as a "C-zero cassette" whilst such a cassette constructed for video use is known as a "V-zero cassette". The first step in loading is to cut the leader into two separate leader lengths. The magnetic tape to be loaded is then spliced to one length of leader and the hub to which that leader length is connected is rotated to wind a predetermined length of magnetic tape onto the same hub. The magnetic tape is then cut and its trailing end spliced to the leading end of the remaining leader length so that the two hubs are connected by a leader-magnetic-leader continuous tape sequence.
The above sequence of operations can be carried out as hand work, but in modern practice the operation is mechanised to provide manufacturing speed and uniform product quality. A typical apparatus for performing these operations is disclosed in U.S. Pat. No. 3,637,153. The apparatus disclosed in U.S. Pat. No. 3,637,153 comprises means for holding a supply reel of magnetic tape, means for supporting a tape cassette (eg by its hubs), a splicing assembly comprising a stationary splicing head and first and second moveable splicing heads which are alternately moveable into contiguous relation with the stationary splicing head, means for releasably holding tape ends on the stationary and moveable splicing heads, means for slitting tape supported by the splicing assembly, means for rotating the supply reel and one of the cassette hubs to cause magnetic tape spliced to a leader on the hub to be unwound from the supply reel and wound on the hub in question, and means for applying splicing tape to the abutting ends of leader and magnetic tapes supported by the splicing assembly. In operation, cassette loading commences with the leader ends (ie a cut hub-hub leader length) held on the contiguously disposed stationary head and first splicing head, respectively, and the end of the magnetic tape held on the second splicing head. The first moveable splicing head is then moved away from the stationary splicing head and the second moveable head with its held end of the magnetic tape is moved into contiguous relation with the stationary head. This brings the leader held on the stationary head into end-to-end abutment with the magnetic tape and the two are then spliced together. The spliced tape is then wound onto the cassette hub to which the leader is secured and winding continued until a predetermined length of magnetic tape is then slit. The second moveable splicing head, which continues to hold the leading edge of the magnetic tape supply, is then removed away from the stationary head leaving a trailing end of magnetic tape from the newly loaded cassette held by the stationary head. Moving the first moveable splicing head back into contiguous relation with respect to the stationary head juxtapose the leading end of the remaining cut leader length in abutment to the trailing end of magnetic tape held on the stationary head. These two ends are then spliced to complete the production of a loaded cassette. The apparatus described in U.S. Pat. No. 3,637,153 includes control means for selectively operating the components of the apparatus to perform the above-described operations in the sequence given.
In tape winding operations, the magnetic tape is pulled into the cassette by a motor driving the hub inside the cassette. This means that the tape is under greatest tension just before it enters the cassette. The tension in the tape reduces at every point of mechanical contact with the guides, cleaning fabric and so on on the tape winding path. Design considerations mean the last guide before the tape enters the cassette is often used as both a rotating guide around which the tape runs at maximum tension during winding and the extracting device used to pull the leader from the cassettes. In order to do this, it must be of sufficiently small diameter to pass through the appropriate aperture in the cassette to take up a position under the leader tape. However, since tape winding takes place at speeds up to 20 m/sec, the rotational speed of the rotational guide has to be very high and this can lead to tape damage when using small diameter final guides, particularly under tension.
Tape winding speed is monitored by a tacho device in contact with the tape. The thinness of the tape being wound and the requirement that is must not be stretched or damaged is responsible for practice dictactin that winding takes place at low tensions. This is exacerbated by the traditional practice dictated by design considerations of locating the tacho wheel upstream of the splicing surface and receiving tape issuing from the supply pancake. Coupled with the high speed of winding, it is difficult to keep the tape in contact with a conventional tacho wheel.
Equipment made by Tapematic and Jing-Wa overcome the problems associated with small diameter final guides by constructing the final guide leader extraction arm as an air bearing in which a plurality of air apertures are used to eject air between the guide surface and the tape as lubrication. Otami equipment combines a retractable large diameter final guide with a leader extraction arm. The extractor extracts leader tape from a lid-down oriented cassette and introduces the leader tape to a splicing surface. A retracted large diameter guide advances into the tape loop and is then displaced laterally within the loop until it contacts the tape adjacent to the input mouth of the cassette. The leader having been extracted, splicing and winding then follow whilst both the guide and extractor remain in contact with the tape.
Print tapes for use in impact printers, such as used in an office context driven by computers, is conveniently made in cassette or cartridge form. In general terms, such tape is subject to the same handling requirements as magnetic tape and broadly similar winding machinery can be deployed for loading such tape into cassettes.